This invention relates generally to packaging and more particularly to flexible packaging.
Flexible containers formed of sheet materials have gained wide acceptance in the trade for holding foodstuffs, powdered chemicals, or other air-perishable materials therein. One common type of flexible package container is the so-called "gussetted package". Such packages are typically made of a web of flexible stock material, e.g., polyethylene, polyester, polypropylene, metal foil, or combinations thereof in single or multiple plies. The web is formed into a tubular body having a front panel, a rear panel, and a pair of gussetted side panels. Each gussetted side panel comprises a pair of gusset sections having a central fold edge interposed between a pair of outer fold edges. The marginal edges of the front and rear panels of the package form the outer fold edges. The outer fold edges of one side of both panels and the interposed central fold edge define respective gusset sections therebetween. Those sections are subadjacent (i.e., underlie) the marginal edges of their associated panels.
The lower end of many such prior art gussetted packages are commonly permanently, e.g., heat, sealed along a line extending transversely across the width of the package close to the bottom edge of the package. The upper end of each package is commonly left open to form a mouth for filling, and in many cases, emptying, the package. In particular, it is common to form the mouth of the package with some sealable, e.g., heat sealable, means. This enables the package to be sealed at its mouth after the package is filled with the desired contents.
In U.S. Pat. No. 4,913,561 entitled Gussetted Flexible Package With Presealed Portions and Method of Making the Same, which is assigned to the same assignee as this invention, and whose disclosure is incorporated by reference herein there are disclosed flexible containers having a mouth extending between the gussets which can be readily sealed by the application of heat and pressure thereto to form a readily peelable mouth through which the contents of the package may be poured.
While such packaging is suitable for its intended purposes, the readily peelable seal may not be strong enough for some applications, e.g., holding powdered chemicals which may be subject to harsh or rough handling. Moreover, the use of a readily peelable mouth in a package adds to the cost thereof. Thus, for some applications it may not be desirable to utilize peelable means at the mouth of the package to enable it to be peeled open to pour the contents of the package therethrough.
Tear notches have been used to serve as means for providing easy opening of non-gussetted packages. Many examples of such packages are in use today. One such package comprises a pair of gussets on opposite sides of a bottom seal and a gusset on only one side of the top seal. The other side of the top seal is not gussetted to form a pour spout. In order to open the pour spout the non-gussetted portion at the side of the top seal is provided with a tear notch. Accordingly, the pour spout can be opened by tearing the package from its tear notch.
The use of tear notches in non-gussetted packages or in non-gussetted portions of packages to form an open pour spout has proved to be a less than optimum packaging approach. This results from the inability of such packages to maintain their shape.
Thus, the need presently exists for a gussetted flexible package having strong non-peelable seals but which includes means for producing a pouring spout, with little or no additional cost.